A fast food restaurant claims that the mean waiting time isn't equal to 3.9 minutes. A random sample of 26 customers revealed mean waiting of 2.7 minutes with sample standard deviation of 0.4 minutes. Develop a 90% confidence interval, then test the restaurant's claimed by checking to see if the claimed waiting is in the confidence interval or not, answer yes or no.
Suppose that the population has normally distribution and population standard deviation is unknown. Develop the Confidence interval and find out if the value 3.9 is in the Confidence interval. You must state whether or not the Confidence interval contains 3.9, answer yes or no.
Please show work. Step by step process.